Radio frequency coil for open magnetic resonance imaging system
First Claim
1. A quadrature coil for operation at a radio frequency in an open MRI system, the MRI system having a polarizing magnet with opposed pole faces for establishing therebetween a polarizing field axis, the coil comprising,a first conductor array providing separated and substantially parallel conductor elements positioned along a first conductor axis extending across the polarizing field axis to opposed, common connection points;
- a second conductor array providing separated and substantially parallel conductor elements positioned along a second conductor axis extending across the polarizing field axis to opposed, connection points and substantially perpendicular to the first conductor elements;
a combiner/splitter electrically communicating with a connection point of each of the first and second conductor arrays to join the connection points with a signal line so that a signal path between said signal line and the common connection point of the first conductor array has a substantially 90 degree phase difference from a signal path between the common signal line and the connection point of the second conductor array; and
an isolation circuit coupled between the first and second conductor arrays to act as a blocking parallel resonance at the radio frequency.
1 Assignment
0 Petitions
Accused Products
Abstract
A quadrature coil suitable for use with an open frame MRI system provides crossing pairs of arrays of parallel conductor elements, respectively. Compact configuration is provided through use of an isolating circuit for incorporating parasitic capacitances at the resonance frequency of the coil into a blocking parallel resonance. Termination of the parallel conductor elements may be accomplished by equal impedance node connectors formed from branching pairs of conductors or a triangular least resistance connection form. RF shields are provided by pairs of conductive sheets containing eddy current reducing slots aligned with the parallel conductors elements of the coil.
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Citations
9 Claims
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1. A quadrature coil for operation at a radio frequency in an open MRI system, the MRI system having a polarizing magnet with opposed pole faces for establishing therebetween a polarizing field axis, the coil comprising,
a first conductor array providing separated and substantially parallel conductor elements positioned along a first conductor axis extending across the polarizing field axis to opposed, common connection points; -
a second conductor array providing separated and substantially parallel conductor elements positioned along a second conductor axis extending across the polarizing field axis to opposed, connection points and substantially perpendicular to the first conductor elements;
a combiner/splitter electrically communicating with a connection point of each of the first and second conductor arrays to join the connection points with a signal line so that a signal path between said signal line and the common connection point of the first conductor array has a substantially 90 degree phase difference from a signal path between the common signal line and the connection point of the second conductor array; and
an isolation circuit coupled between the first and second conductor arrays to act as a blocking parallel resonance at the radio frequency. - View Dependent Claims (2, 3)
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4. A quadrature coil for operation at a radio frequency in an open MRI system, the MRI system having a polarizing magnet with opposed pole faces for establishing therebetween a polarizing field axis (B0), the coil comprising:
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a first conductor array providing separated and substantially parallel conductor elements positioned along a first conductor axis extending across the polarizing field axis to opposed connection points;
a second conductor array providing separated and substantially parallel conductor elements positioned along a second conductor axis extending across the polarizing field axis and substantially perpendicular to the first conductor array to opposed connection points;
an RF shield positioned between an adjacent pole face and the first and second conductor arrays for providing a conductive surface interrupted by channels substantially aligned with both the first and second conductor axis; and
a combiner/splitter electrically communicating with a connection point of each of the first and second conductor arrays to join the connection points with a signal line so that the signal path between said signal line and the connection point of the first conductor array has a substantially 90 degree phase when compared with the signal path between the common signal line and the connection point of the second conductor array. - View Dependent Claims (5, 6, 7)
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8. A quadrature coil set for operation at a radio frequency in an open MRI system, the MRI system having a polarizing magnet with opposed pole faces for establishing therebetween a polarizing field axis, the coil comprising:
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A.) a first quadrature coil positioned at a first pole face and having (a) a first conductor array providing separated and substantially parallel conductor elements positioned along a first conductor axis extending across the polarizing field axis to opposed connection points, and (b) a second conductor array providing separated and substantially parallel conductor elements positioned along a second conductor axis extending across the polarizing field axis to opposed connection points in a direction substantially perpendicular to the first conductor array;
B.) a second quadrature coil positioned at a second pole face and having;
(a) a third conductor array providing separated and substantially parallel conductor elements positioned along the first conductor axis extending across the polarizing field axis to opposed connection points, (b) a fourth conductor array providing separated and substantially parallel conductor elements positioned along the second conductor axis extending across the polarizing field axis to opposed connection points in a direction substantially perpendicular to the first conductor array;
C.) interconnection leads connecting the first and third conductor arrays in series through their connection points; and
D.) interconnection leads connecting the second and fourth conductor arrays in series through their connection points;
whereby current flow direction through the first and third conductor arrays is opposite to current flow direction through the second and fourth conductor arrays, respectively. - View Dependent Claims (9)
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Specification